Electrocoagulation reactor

ABSTRACT

An electrocoagulation reactor is provided for treating waste water and removing contaminants therefrom. The reactor is typically a six sided rectangular water tight housing which has an inlet pipe and an outlet pipe. There are a multiplicity of charged plates located parallel to one another within the housing. Adjacent plates are typically oppositely charged and water will pass between the plates as it flows through the reactor. The electric field between the plates will help encourage coagulation of waste matter which then may be removed from the waste water downstream of the electrocoagulation reactor.

FIELD OF THE INVENTION

[0001] Electrocoagulation reactors, more specifically, aelectrocoagulation reactor with the plates in parallel to the flow ofthe water.

BACKGROUND OF THE INVENTION

[0002] Wastewater, such as wastewater from factories or manufacturingplants, must be treated for contaminants before it is discharged intothe environment. Water for use in industrial or other manufacturingprocess often requires treatment before use to alter its chemical orphysical characteristics. Electrocoagulation is an electro chemicalprocess that simultaneously removes heavy metals, suspended solids,organic and other contaminates from water using electricity instead ofexpensive chemical reagents. Electrocoagulation was first used to treatbilge water from ships. The Electrocoagulation process passescontaminated water between metal plates charged with direct current.While the term “wastewater” is often used herein, the term is to beunderstood to mean any water from which one may wish to remove a“contaminant” even though the contaminant may not necessarily be amaterial that would be harmful to ones health.

[0003] Additional background in the specifications regardingelectrocoagulations may be found in U.S. Pat. No. 5,928,493, thespecifications or drawings of which are incorporated herein byreference.

[0004] Applicant's provide, in the invention disclosed herein, anunpressurized electrocoagulation reactor, with plates in parallel to theflow of the water, which reactor has the capability of treating a higherflow of wastewater than has heretofore been available.

SUMMARY OF THE INVENTION

[0005] Applicants provide for these and other objectives in a parallelflow reactor comprised of one or more reactor cells. Each cell typicallyincludes a tank containing a cartridge, the cartridge having a framewith a multiplicity of aligned plates therein. Water flows through thetank, typically up from the bottom of the cartridge-held plates over atop wall of the cartridge in “water fall” (cascading) fashion and outthe tank for further processing or use. Applicant provides anelectrocoagulation cell with an open top, one that is unpressurized andobtains, at least in part, the flow of water under the impetus ofgravity.

[0006] Applicants provide for these and other objectives in anelectrocoagulation reactor comprising, in a preferred embodiment, twoelectrocoagulation cells placed “in series.” By “in series” applicantmeans that a molecule of wastewater will flow between two adjacent platein the first cell of a reactor, out of the first cell of the reactor andbetween a second pair of plates in the second cell of theelectrocoagulation reactor. Applicants provide, in a preferredembodiment of a two-cell electrocoagulation reactor, cells which are setin series. This is to be compared with the arrangement in a “seriesflow” reactor in which a single molecule of water would follow aserpentine path and pass between a multiplicity of plate pairs within asingle cell.

[0007] Applicants provide for these and other objectives in a parallelflow, open top electrocoagulation reactor having one of more cells inseries, wherein each cell typically contains a cartridge capable ofbeing lifted out of the tank of the cell. In other words, applicantsprovide for a “cartridge” which is capable of receiving plates therein,and then dropped into, from the open top, the tank of aelectrocoagulation cell, and, when the plates need replacement, thecartridge may be lifted out of the electrocoagulation tank so that theused up plates may be changed out with new plates at a point removedfrom the electrocoagulation tank. This and other advantages ofapplicant's cartridge will be apparent with reference to specificationsand drawings contained herein.

[0008] Applicants' unique cartridge also provides for the ability toaccept plates of differing dimensions so, for example, a singlecartridge may either receive plates with a given height, or, if the userrequires less treatment capacity, to receive plates of a shorter orgreater height. Thus, a user may, instead of using a reactor with adifferent size tank, simply use the same tank and same cartridge, butuse, if the conditions require, plates with less or greater surfacearea.

[0009] Applicants provide for efficient treatment of wastewater in aparallel flow, open top, cartridge-receiving electrocoagulation cell inwhich there are a multiplicity of plates, at least some of the platesbeing alternately charged positive and negative, sometimes with an“intermediate” or uncharged plate (or plates) between adjacent positiveand negative plates.

[0010] Applicants provide for these and other advantages and objects inan electrocoagulation reactor consisting of electrocoagulation cells inwhich, beneath the plate bearing cartridges and in fluid communicationtherewith is a solids sump with a drain attached thereto for removingfrom a tank of the electrocoagulation cell, waste sediment that hasresulted from the electrocoagulation of waste particles and for removalof the collected sediment from a drain therein.

[0011] Applicants provide for these and other advantages and objectives,in an electrocoagulation reactor system comprising a unique stand forcooperatively engaging the tank and cartridge of the electrocoagulationcell to provide direct weight-bearing support of the plates in thecartridge of the electrocoagulation cell.

[0012] Applicants additionally provide a plate for use with any type ofelectrocoagulation reactor system, which plate contains cutouts in thewalls there through, the cutouts for more effective treatment ofwastewater passing adjacent the plate.

[0013] Applicants additionally provide, for use with any reactor, arecirculation pump and recirculation loop. The recirculation pump andloop takes some, but not all, of the water flowing out of a reactor andrecirculates it through the reactor by, typically, routing it upstreamof the intake of the reactor. This allows the user to maintain a greaterflow of fluid through the reactor than the net flow of water treated.

[0014] Applicants also provide for a novel dissolved air floatation cellfor the treatment of wastewater using an electrocoagulation reactor.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 illustrates an isometric view of a single parallel flowcell.

[0016]FIG. 1A is a side elevational view of a pair of parallel flowreactor cells in series.

[0017]FIG. 1B is a partial elevational view of a multiplicity ofparallel plates for use in Applicants' novel electrocoagulation reactor.

[0018]FIGS. 1C and 1D are partial side elevational views illustratingthe manner in which Applicants' cartridge may be modified to containplates of different heights.

[0019]FIG. 1E is a partial isometric view of a device and method forraising the height of the weir of Applicants' electrocoagulation cell byattaching a riser thereto.

[0020]FIG. 1F illustrates a device for maintaining separation betweenthe wall of the tank and the wall of the cartridge, in partial view,cutaway isometric.

[0021]FIG. 2 illustrates a side elevational view of a parallel flowelectrocoagulation reactor.

[0022]FIG. 3 illustrates a front view of the electrocoagulation cellillustrating a pair of drains 12H to remove liquids therefrom.

[0023]FIG. 4 illustrates an isometric view of two parallel reactor cellsin a single tank.

[0024]FIG. 5 is a front elevational view of a single reactor tank havinga pair of cartridges therein and a multiplicity of circulation drainsand inlets.

[0025]FIG. 6 is a rear view of the illustration set forth in FIG. 5above.

[0026] FIGS. 7A-E are various view of a stand for use with Applicants'electrocoagulation reactor.

[0027]FIGS. 8A and 8B are isometric views of different embodiments ofplates for use in Applicants' electrocoagulation reactor.

[0028]FIGS. 9 and 10 are block diagrams of Applicants' novelrecirculation pump and recirculation loop for use with a wastewaterreactor.

[0029]FIGS. 11A and 11B are side and bottom elevational views of adissolved air floatation cell for use with Applicants'electrocoagulation reactor.

[0030]FIGS. 12A and 12B are alternate preferred embodiments of adissolved air floatation cell for use with Applicants' waste treatmentprocess.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0031] Turning to FIG. 1 it is seen that applicant provides anelectrocoagulation reactor 11 which may be comprised of a singleelectrocoagulation cell 10 or two or more electrocoagulation cells 10and 10A placed in series, see FIG. 1A.

[0032] Attention will be first directed to FIG. 1 to explain thestructure and function of an electrocoagulation cell 10. Once this isunderstood, it will be seen that the structure and function ofelectrocoagulation cell 10 is nearly identical to second cell 10A (SeeFIG. 1A). Turning back to FIG. 1, it is seen that firstelectrocoagulation cell 10 is comprised of a typically open topped celltank 12 and a first cartridge 14 resting inside the tank 12 inwastewater WW. Tank 12 is typically watertight and may be rectangular,or any other shape and typically includes an open top 12Q. In any case,cell tank 12 is typically unpressurized and may be made of fiberglass,steel or plastic, or in fact any other suitable material which wouldprovide watertight sealing and would not react with the wastewater. Celltank 12 is seen to have, in the preferred embodiment illustrated in FIG.1, four sidewalls, 12A, 12B, 12C and 12D set perpendicular to oneanother so as to provide the rectangular structure illustrated ascartridge receiving portion 12I of the tank 12. Depending belowcartridge receiving portion 12I and integral therewith and in fluidcommunication with cartridge receiving portion receiving 12I is sumpportion 12J of tank 12. It is seen with reference to FIG. 1 thatcartridge receiving portion 12I has an open bottom 12R. It is also seenthat cartridge receiving portion 12I of cell tank 12 includes arectangular cartridge support ledge 12F and a cartridge support anddrain ledge 12G. The four ledges directed inboard along the perimeter ofthe sidewalls act as a base to hold the cartridge 14 along the loweredges, so water may enter the cartridge from below. The function of theledges is to support the lower perimeter of the first cartridge 14 as itrests in cartridge receiving portion 12I. Additional features of celltank 12 include an upper perimeter 12E defined by the upper edges ofsidewalls 12A, 12B, 12C and 12D. Depending below cartridge support anddrain ledge 12G are one or more drains 12H which will accept wastewaterfrom a transfer chamber 13 (see FIG. 1A). The transfer chamber 13 is thespace between a front wall 14B of the cartridge 14 and sidewall 12A ofthe cell tank 12.

[0033] Turning now to sump portion 12J it is seen that this portion ofcell tank 12 is located below open bottom 12R of cartridge receivingportion 12I so as to collect waste solids and suspended materialssettling out from between plates 20 of first cartridge 14 (see FIG. 1A),at the bottom thereof for removal through a sump drain 12P. Sump portion12J typically includes one or more canted or slopped sidewalls hereshowing four sidewalls designated 12K, 12L, 12M and 12N so as to funnel,under the impetus of gravity, settling solids to sump drain 12P forremoval therefrom.

[0034] It is seen that first cartridge 14 is typically not mechanicallyfastened to cartridge receiving portion 12I or any other portion of celltank 12, but merely rests along a portion of the bottom of cartridgereceiving portion 12I here resting along the edges below rear wall 14Aand front wall 14D on cartridge support ledge 12F and cartridge supportand drain ledge 12G, respectively and on ledges below the sidewalls ofthe cartridge. First cartridge 14 is typically rectangular shaped anddimensioned for the receipt within cartridge receiving portion 12I ofcell tank 12 so as to allow water coming in through inlet 13M tocirculate up through a pair of adjacent plates 20 and to cascade overthe weir 14J (or top lip) of front wall 14B into the transfer chamber 13(See FIG. 1A). In other words, a close examination of first cartridge14D as set forth in FIG. 1 will reveal that rear wall 14A and the twoend walls 14C and D are the same height but that front wall 14Bcomprises an upper perimeter or lip defining a weir 14J that is lower.

[0035] Moreover, both rear wall of 14A and front wall 14B have verticalslots 14E on their inner faces for the acceptance of plates 20 in“slotting fashion.” Plates 20 are held along a pair of removed verticaledges and suspended between the front wall 14B and the rear wall 14Awith the entire cartridge having an open top 14H and an open bottom 14Ifor water to pass up through the plates 20 as illustrated in FIG. 1A. Itis seen that first cartridge 14 also includes handling straps 14G whichmay contain a hole at the removed ends thereof. The straps may extenddown the vertical sides of the cartridge 14 and beneath the walls tosupport them from below, and above the walls of the cartridge 14 toengage one or more of hooks (not shown) to provide a mechanical assistto lift the entire cartridge 14, with the plates 20 therein, out of theopen top 14H of the tank 12 for replacement of the used up plates of thecartridge 14, “offline.” Following plate 20 replacement, the cartridge14 is reinserted into the tank.

[0036] The function of first cartridge 14 is to provide structure todefine and maintain a passageway for water entering through one or moreinlet 3 13M such that the water will pass through a space between a pairof a multiplicity of pairs of plates 20 maintained between the front andrear walls of the cartridge 14, in such a manner that the water spillsover weir 14J into transfer chamber 13 for leaving cell tank 12 throughdrain 12H. As the wastewater proceeds between the pair of oppositelycharged plates 20 and any intermediate plates therebetween it will besubject to an electric field which will promote electrocoagulationprocesses known in the prior art.

[0037]FIG. 1A illustrates that a preferred alternate embodiment ofapplicants' present invention uses a second electrocoagulation cell 10Aplaced in series with the first electrocoagulation cell 10, thecombination being referred to as electrocoagulation reactor 11. That is,it is seen that FIG. 1A illustrates raw water WW (untreated water)entering through inlet 13M and passing between the plates of firstcartridge 14 and then passing over weir 14J and out drain 12H. It isseen that the water then passes into inlet 16M of second tank 16. It isseen that second cell tank 16 includes a second cartridge 18 which issubstantially identical to first cartridge 14 in all material componentsthereof and its function. Water overflowing second weir 16J intotransfer chamber 13A will exit the electrocoagulation reactor 11 throughdrain 16H (assuming this is only a two-cell reactor). It is found thatproviding two cells in series, the second cell either being lower orhaving a weir lower than the first cell 10 allows water to flow throughthe cells under the impetus of gravity (no pump necessary). Further, theuse of a pair or more of series engaged cells has proven to be effectivein removing contaminants from the water. While each of the two cellsillustrated in FIG. 1A includes its own separate tank 12 and 16,respectively, it is possible to set up a single large tank for twoindividual cells, each cell being defined by its own cartridge and,further defined, by the passageway of a single water molecule through asingle pair of plates in the first cartridge, and then passing through asingle pair of adjacent plates in the second cartridge and then out thecell or tank. Applicants may provide a reactor containing two or morecartridges set up in series, each cartridge with its own tank asillustrated in FIG. 1A.

[0038]FIG. 1B illustrates a top elevational view of a portion of thesidewall and end wall of a cartridge and the manner in which positivelyand negatively charged plates may carry an intermediate or unchargedplate therebetween to assist in the effectiveness of theelectrocoagulation process. That is, FIG. 1B illustrates a multiplicityof parallel plates including a positively charged plate 20A,intermediate (neutral or uncharged) ungrounded plate 20B and anegatively charged plate 20C. These plates are attached to a rectifierand the voltage therebetween may be adjustably set, typically to betweenzero and up to 50 volts DC.

[0039] In a preferred alternate embodiment there may be more than oneimmediate or neutral plate between adjacent positively or negativelycharged plates or, there may be no neutral plates at all betweenadjacent negatively and positively charged plates. However, it is seenthat whatever configurations the sets may take they are disposedparallel to one another as set forth in FIG. 1B.

[0040] In first preferred embodiment in cartridge 14/18, the plates 20,as seen in FIG. 1A will extend from at or near the top of the cartridgeto at or near the bottom of the cartridge. That is, the bottom edge ofthe multiplicity of plates may be adjacent to the top and bottom of thecartridge. However, applicants provide in a novel cartridge means toaccept shorter plates, that is, plates that do not extend fully down tothe bottom of the cartridge, in an effort to control the effectivenessand handling of the cartridge of the cell when handling a waste waterload that is less than the maximum capacity of the reactor.

[0041] As a bit of background, reactors are typically rated in theirability to handle wastewater by the maximum amount of wastewater flowthat can be treated by a given reactor. For example, a reactor may bedesigned to treat wastewater with a given conductivity/resistivity rangeat a flow of 500 gallons per minute. This rating for that given reactoris for a reactor with full plates as illustrated in 1A. However, thesituation may arise where, for example, water with reduced flow rate isbeing treated and therefore the same applied voltage, say, for example,48 volts may be used but the user may “size” the cartridge with smallerplates for easier handling and increased efficiency. It is found to beadvantageous to use the same cartridge and provide a means for insertingshorter plates so as to efficiently handle wastewater with a lower flowrate than the maximum capability of the reactor cell. For example, auser may wish to purchase a cell of 500 gallons per minute maximumcapacity even though the current demand of that user is only, say, 200gallons per minute. It may be more economical to purchase a larger unitand use shorter plates and, when the requirements of the user increaseto use the same cartridge and purchase longer plates. Applicants haveprovided for a mechanism in their unique cartridge system which willallow for the acceptance of shorter plates therein.

[0042] To “size” a reactor, one could build eight to ten different sizetanks and cartridges to cover the different flow rate demands from, forexample, 100 gallons per minute to 1500 gallons per minute. However, byusing Applicant's design one can cover the entire range with only twodifferent size tanks and cartridge by creating a flexible cartridgesystem allowing use of different size plates. In this way, a singlecartridge design can be used to accommodate flow rate demands from 100gallons per minute to 500 gallons per minute and another singlecartridge design can accommodate flow rate demands of 500 gallons perminute to 1500 gallons per minute. This system is illustrated in FIGS.1, 1C, 1D and 2. It is noted that both the front and the rear wall havea horizontally cut notch at a pre-described location above the bottomedge of the front and the rear wall. Notch 22 is dimensioned for snugreceipt of a stop member (24), typically a rectangular, elongated membersized to wedge snugly into notch 22. With notch 22 along the insidesurface of both the front wall and the rear wall the same distance abovethe bottom edge of each of those walls and with the stop members (24)firmly inserted in the notches, the cartridge can accept a shorter plateby receiving the lower edge of the plates (20) against the upper surfaceof the stop member 24 (See FIG. 1D).

[0043] Moreover, with water being treated at less than the maximum ratedcapacity, it is beneficial to raise the height of weir 14J/16J todecrease the amount of “freeboard” or the amount of exposed plate abovewater level WL (exposed plate is “wasted” when the rest of the plate isbeing consumed). A method for increasing the height of weir 14J/15J isillustrated in FIG. 1E. It is seen with respect to FIG. 1E a riser 26may be provided which is simply a rectangular, elongated member shapedto fit on top of weir 14J/16J by means, for example, of a dowel 26A/hole26B combination as illustrated in FIG. 1E. That is, a series ofvertically 11 aligned holes 26B may be provided projecting downward fromthe top surface of weir 14J/16J and a pair of identically spaced anddimensioned holes provided in riser 26 projecting from the underside ofriser 26 up into the riser 26. With this arrangement, holes in the riserand weir dowels 26A may be used to snugly seat riser 26 to weir 14J/16Jto effectively raise the level the water which will reach before itpours over the weir 14J/16J and, likewise, would decrease the amount of“freeboard” on the steel plates. The reason for decreasing the amount offreeboard is that it represents waste of the plate. Ideally, thereshould be almost no freeboard and the entire plate should be consumed inthe electrocoagulation process.

[0044] Applicant's concept of sizing the plates for a flow rate of lessthan the maximum capacity of the electrocoagulation cell at a givenvoltage for a given set of treatment parameters for water gives the userthe possibility of using a single “universal” cartridge—that is, acartridge whose plates or other variables can be sized so that it willeffectively run water with requirements substantially less than themaximum capability of the unit, through the use of smaller plates.Smaller plates are, again, advantageous as they make handling of thecartridge which, loaded with plates, may weigh several thousand pounds,much easier. Applicants' provide for a universal cartridge with theability to easily alter the cartridge to accept the plates withdiffering dimensions, while also being able to alter the weir 14J/16Jheight of the cartridge 14 to adapt to the smaller plates. Some of theelectrocoagulation cells can use up to 7,000 pounds of steel plates in asingle cartridge. Therefore, the decreased lift-out and handlingrequirement may be readily appreciated.

[0045] One could lift out Applicants' cartridge, which consists of aframe around the plates, and then, with the cartridge removed from thetank, change out the plates. In other words, plates don't have to bechanged out directly from the tank. Indeed, one can withdraw onecartridge and >immediately insert a second cartridge, full of platesand, at their leisure, remove the wasted steel plates from the firstcartridge. In other words, the lift out cartridge provides that theplates can be removed “in mass” and “replaced in mass,” a system wherethe electrocoagulation reactor does not have to be shut down or be takenoff-line while the plates are changed out.

[0046] Applicants provide yet another advantage in providing in FIG. 1F,structure defining bumpers 28. This will allow the cartridge 14, as itis lifted in or out of the tank 12 to be protected from banging directlyinto the inside surface of the sidewalls of the tank or the bottom ofthe tank. Bumpers 28 may be made out of hard rubber or any othersuitable, durable, non-reactive material.

[0047]FIGS. 4, 5, and 6 all illustrate an alternate preferred embodimentof an electrocoagulation cell 10 which doubles the capacity of theaforementioned electrocoagulation cells by providing tank 12 with alarger volume, typically about twice to four times the volume of thecell set forth in the earlier embodiments. The size of the cartridge 14is also increased, that is, to handle many more plates. An intermediatewall 30 is provided in the cartridge for structural support. It is alsoseen that there may be a pair of sump portions 12J each one with a drainsump 12P. The drain sumps are provided to remove any sediment settlingin the sumps. There also may be two or more drains 12H.

[0048] Applicants' open top, unpressurized parallel flow reactor mayhave a number of plate arrangements including: plus minus plus minus:plus n minus n plus n minus, etc. The recirculation loop may recirculatethrough one or more cells of the reactor. Typically, water will flowthrough each individual solid reactor from bottom to top, to assist inthe escape of gases. Individual plates of each cell may be tabular innature and made from iron, steel, aluminum or other material. They mayinclude “cutouts” in various shapes (see FIG. 8B) to help generate anon-uniform and more varied e-field between the plates. Extra difficultwaters may be treated a number of passes through the cells through theuse of a recirculation pump (see below). There may be a number of waterinlets across the bottom of the housing of the parallel flow reactor tohelp generate even flow across the plates.

[0049]FIGS. 7A through 7E illustrate components of Applicant's cellstand 40. FIG. 7A represents a left and right side assembly for therectangular stand. FIG. 7B is a rear assembly for the stand. FIG. 7C isa front assembly for the stand. FIG. 7D is a view of a cross brace foruse with the rear assembly of the stand. FIG. 7E is another cross bracefor use with the front assembly of the stand.

[0050] When bolted together the front assembly, rear assembly and twoside assemblies form a rectangle which will vertically support the celltank 12 at a point immediately below the lower perimeter of thecartridge 14 that is placed in the tank so as to avoid any sheer or flexloading on the bottom walls of the tank. That is, when bolted togetherthe cell stand 40 will have upper perimeter walls that are dimensionedidentical to at least a portion of the lower perimeter of the cartridge.

[0051] It is seen that electrocoagulation cell stand 40 has a number ofvertical support legs 42 for providing a vertical support to tanksupport perimeter members 44A, 44B and 44C. The tank perimeter supportmember 44A provides support to the left and right side of the tank, 44Bprovides support to the tank directly beneath the rear wall of thecartridge and vertical support perimeter 44C provides vertical supportto the tank directly below the front wall of the cartridge. Fasteners45A are used to fasten the stand together by engaging bolt holes 45B.Note that both the rear assembly of the stand and the front assembly ofthe stand include cross braces 46 and 48, with cross brace 46 on therear assembly of the stand including a vertical support leg 42 forreaching all the way to the floor. (See FIG. 7B) Compare this to FIG. 7Cwhich illustrates the front assembly of the stand. Here there is nothird leg. This is because the tank illustrated in FIG. 1 has a soliddrain 12P which projects horizontally out from the side wall. Further,note with reference to FIG. 1 that placement of a stand beneath the tankso as to brace the stand directly beneath the lower perimeter of thecartridge requires that the tank support members 44A, 44B and 44C mustbe attached so that vertical support member 44C will lay between the twodrains 12H and sump sidewall 12K. The rear tank support perimeter 44Cwill lay between the two inlet blanks 13M and the sidewall of sumpportion 12J. However, the third vertical support leg 42 shown in FIG. 7B(the one between the two outer support legs) is used since there is nodrain on the rear portion of the tank. The two sidewall portions of tanksupport perimeter 44A will lay beneath the sidewalls of the lowerperimeter of the cartridge and snugged against the sidewalls definingsump portion 12J. Applicant's unique cell stand 40 has the uniqueability to bolt together around the upper perimeter of sump portion 12Jof cell tank 12 in an manner that by, unbolting the six (6) bolts andbolt holes, the six (6) fasteners illustrated in FIGS. 7B and 7C one cantake apart the stand around the sump portion so as to provide clearancefor the solid drain 12P.

[0052]FIGS. 8A and 8B illustrate the first plate 20, which is seen to betabular and solid. Applicants have found that efficiency may beincreased by providing an alternate preferred embodiment here plate 21which includes cutouts 21A in the walls thereof. It is believed thatcutouts generate disturbances in the uniformity of the electromagneticfields between the plates and therefore assist in the efficiency of theelectrocoagulation units. However, they typically are also moreexpensive than providing plates without cutouts as set forth in FIG. 8A.

[0053] Typically, a reactor is rated at a given flow rate and works mostefficiently at that flow rate. For example, a 350 GPM parallel flowelectrocoagulation reactor is preferably not run at less than 50 gallonsper minute. Applicants provide, in FIGS. 9 and 10, a means forrecirculating a portion of the water exiting an electrocoagulationreactor and thereby achieving a net flow downstream from the reactor oftreated water of a flow rate less than that of the water flowing throughthe reactor. For example, a flow rate of 200 gallons per minute may bemaintained through a reactor with a recirculation loop drawing off partof the water exiting from the electrocoagulation reactor andreintroducing it upstream of the inlet of the electrocoagulationreactor. A net flow of, for example, 100 gallons per minute of treatedwater may result while maintaining a given flow rate at 200 gallons perminute through the electrocoagulation reactor. In other words, anoverall flow rate of 200 gallons per minute (for example) may bemaintained through the electrocoagulation reactor portion of the systemby using a recirculation pump and recirculation loop while treating anet amount of water equal to, for example, with reference to FIG. 9, 100gallons per minute. The use of a recirculation loop may increase theresidence time for a particular waste that needs extra treatment. Thealternative would be to have two reactors, two rectifiers etc., whichwould be costly.

[0054] A recirculation loop may be used with any of Applicant'sembodiments disclosed herein, in fact with any other electrocoagulationreactor or system. It provides a fairly simple and inexpensive means tomaintain a given flow rate through a reactor while increasing theresidence time of the water in the reactor (compared to a single pass)and, for decreasing the net flow of water treated but maintaining ahigher flow rate through the reactor. For example, assume upstream pump(100) is pumping 100 gallons a minute from a water source (WS). Reactor(102) may be a 350 gallon per minute reactor. At this flow rating, thereis sufficient flow through the reactor to properly scrub the plates andefficiently treat the water. One can use a recirculation pump (104)providing flow at the rate of 250 gallons per minute to provide a flowrate through a reactor of 350 gallons per minute. Yet the net treatmentrate is 100 gallons per minute of waste water flow downstream from arecirculation junction (106). In fact, Applicant's may increase the flowrate through a reactor providing a flow rate greater than the rating forthe reactor, which flow rate may provide additional water velocity toscrub the plates. For example, a flow rate of 400 gallons per minute maybe provided through the reactor while the net waste water treatment maybe 100 gpm or less.

[0055] Turning now to FIG. 9, Applicant discloses a vessel or othersource of water (WS), the water being industrial and/or biologicaland/or other form of water that may contain contaminants that includeorganic and/or inorganic compositions. The water may be used inagricultural, industrial, domestic treatment or processing of othermaterial, such as sugar cane juice. It may be any water whose physical,chemical and/or biological characteristics may be altered byelectrocoagulation. It is seen that there is an intake pipe havingseveral sections (108A, 108B and 108C) for carrying water from the watersource into a reactor (102), typically an electrocoagulation reactor. Inline with the intake pipe may be an upstream pump (100), upstream of thereactor or the reactor may simply be lower than the water source, the“head” providing impetus to the movement of water to the reactor. Theintake pipe may include a section (108A) between the water source (WS)and the upstream pump (100). A second section of intake pipe (108B), maybe located between an upstream pump (100) and a T Junction or otherjunction (110). Finally there may be a section of intake pipe (108C)between the T Junction or other junction and an intake port (112) of theelectrocoagulation reactor (102).

[0056] The upstream pump (100) may be used to flood the reactor andprovide for water fluid flow through the reactor or the “head” of thewater source may serve the same function. The reactor also has an outletport (114) and outlet pipe sections (114A and 114B). Water leaves theelectrocoagulation reactor at outlet port (114). Some of the water willbe recirculated by exiting the outlet pipe at recirculation junction(106), being drawn by a recirculation pump (104) through a recirculationloop (116). Recirculation loop (116) may include pipe section (116A)upstream of recirculation pump (104) and a recirculation pipe section(116B) downstream of recirculation pump (104). Recirculation pipesection (116B) joins the intake pipe downstream of upstream pump (100)(if any) and upstream of intake port (112), here at junction (110).

[0057]FIG. 10 illustrates an alternate preferred embodiment ofApplicants' novel recirculation loop here being illustrated in use witha reactor comprising two cells, first cell (102A) and second cell(102B). These cells may be either a series flow reactor cell orApplicants' novel parallel flow reactor cell disclosed herein. Here itis seen that Applicants provide a pipe or channel (120) connecting thetwo cells. The first cell (102A) has an inlet (122A) and an outlet(122B). Second cell (102B) has an inlet (124A) and an outlet (124B).Pipe (120) connects the outlet of the first cell to the inlet of thesecond cell. Downstream of the outlet of the second cell is a T-junction(126) at which water may be recirculated through recirculation loop(116) under the impetus of recirculation pump (104) to a point upstreamof inlet (122A) of first reactor (102A). Note that this embodimentillustrates flow through the reactor cells under the impetus of gravityor a “head” between a water source (not shown) which is higher than thefirst cell, and the first cell which is higher than the second cell.Water continuing downstream of T-junction (126) will continue on foreither use discharge, or further treatment, as in settlement,clarification, gas assisted flotation or the like.

[0058] One of the purposes in the parallel flow reactor of providing arecirculation loop is to increase the probability of an ion of wastecomposition being adjacent an oppositely charged plate. In pressurizedreactors (such as Applicants' series flow reactor), sufficient velocityof liquids through the reactor must be maintained for proper removal orscrubbing of the plates of the reactor. On the other hand, inApplicants' parallel flow reactor, which is typically run at atmosphericpressure, sufficient flow is necessary to increase the opportunity of acharged ion to be adjacent an oppositely charged plate.

[0059] One way in which a recirculation loop may be used is to replacethe requirement for multi-cell electrocoagulation reactor. For example,if a treatment job may require 200 g.p.m. through two cells, onefollowing the other (see FIG. 10) for effective treatment. A single cellwith a recirculation loop may achieve equivalent effective treatment ofthe two cell unit.

[0060] Applicants discloses in FIGS. 11A, 11B, 12A and 12B an inventionrelating to a gas-assisted flotation process and apparatus to assist inthe separation of solids and liquids from a slurry, such as a slurrythat would come out of an electrocoagulation reactor cell. Suchinvention may be used to treat wastewater or any other water or fluidthat may be used in or result from a manufacturing process. Applicantsprovide an apparatus and process by which water received from anelectrocoagulation cell may be treated on a continuous basis for theseparation of solids therefrom. For example, water may be treated toremove silicon therefrom for use in the process of manufacturing brownsugar. Indeed, none of the inventions and processes set forth in thisapplication need be confined to “wastewater,” but can be applied to thetreatment of any water whose characteristics are intended to be alteredsuch as for example, by treatment in an electrocoagulation reactor. Thedisclosed invention and process may be used downstream of anyelectrocoagulation cell or other treatment apparatus, including anelectrocoagulation reactor with parallel flow or series flow. Further,some water may be passed through the gas-assisted flotation process andapparatus more than once, as by using Applicants' novel recirculationloop. Under some circumstances, Applicants' novel gas-assisted flotationprocess and apparatus may replace the defoam, sludge, thickener andclarifier processes and apparatus.

[0061] Applicants' novel apparatus, a gas-assisted flotation cell, isprovided which has a conical upper chamber that tapers into a neckportion, which neck portion may include a manifold with gas intake jetsto assist in lifting and propelling floated solids residing above aliquid level, out of a removed end of the neck for discarding or forfurther treatment, as liquid is drawn off the bottom of the main chamberfor either reuse or further treatment.

[0062] Applicants' gas-assisted flotation cell provides advantages notfound in the prior art, including U.S. Pat. No. 5,055,184 (Carpenter, etal. 1991), the specifications and drawings of which is incorporatedherein by reference. The Carpenter reference discloses generally agas-assisted flotation apparatus for separating solids from liquids in aslurry. It comprises a main chamber, an inlet channel from which aliquid slurry may enter, and an upper tapered portion. Gas bubblesattached to solids and particles will tend to float upward in the mainchamber and reside above a liquid line. When the level of liquid issufficiently high in the chamber, the material floating above the liquidline will either drop off through a side exit pipe above the taperedchamber or, if a gas, will rise upward as through a chimney. Thus, theCarpenter reference discloses two exits ports for expelling materialrising above a liquid surface and, in addition, requires a valvemechanism to control the level of liquid in the main chamber.

[0063] Among the advantages of Applicants' present invention over theCarpenter reference is the positive removal, as by compressed gas, offloating solid material out of a removed end of a neck that is in fluidcommunication with the opening at the apex of the tapered walls of theupper chamber. Further, Applicants provide a simple method ofmaintaining a liquid level in the main chamber sufficient to presentmaterial floating above such level to the compressed gas injected intothe neck of the main chamber. Further, Applicants provide a noveltapered lower chamber for collection of sediment therein and, further,for a novel stilling chamber suspended within the main chamber. This andother novel features of Applicants' gas-assisted flotation process andapparatus will be apparent with reference to the drawings below.

[0064]FIGS. 11A and 11B illustrate a dissolved air flotation apparatus200 and FIGS. 12A and 12B show an alternate preferred embodiment,dissolved air flotation apparatus 200A.

[0065] The figures illustrate a main chamber 202 including a taperedupper chamber 204. Main chamber 202 includes vertical sidewalls 206.Applicants provide a tapered lower chamber 208 which descends below thevertical sidewalls 206 and terminates in a drain 210 that may have aplug, removable therefrom, for the draining of sediment that may collectthereon. Tapered upper or lower chambers may be conical or polygonallyshaped.

[0066] Turning back to the upper chamber, it is seen that tapered upperchamber 204 reaches an apex that is open and in fluid communication witha neck 212. In FIGS. 11A and 11B, it is seen that Applicants provide asideport 214 for removal, as by descent under the impetus of gravity, ofsolids floating on the top of a liquid/solids interface. In FIGS. 11Aand 11B, it is seen that there is a removed neck opening 216 for theescape of gases therefrom. However, turning to FIGS. 12A and 12B, it isseen that Applicants may provide, at a suitable location, as for examplein the neck 212 (alternatively directly in the walls of tapered upperchamber 204), an air injector assembly 218. The purpose of the airinjector assembly is to inject air, or other gas, at a suitablelocation, such as in the neck, to assist in lifting the solids and thegases entrapped in the solid/liquid froth that is “floating” above theliquid interface, out of a removed end (216B) of a transport tube 216Awhich may transport the air charged mix. Applicants' air-injectedassembly includes a compressed gas source 218A (for example, an air pumpor a compressed air tank) and a delivery tube 218B for delivery of agas, under pressure to a manifold 218C, which manifold is in fluidcommunication with one or more jet 218D or pressure ports for injectingthe air or other gas under compression into the neck of the main chamberand into a solid/gas froth for removal from the removed end (216B) oftransport tube 216A.

[0067] Applicants' novel gas-assisted flotation apparatus 200, 200A mayinclude a stilling chamber 220, the stilling chamber including an inlettube 222 for carrying a liquid, typically with a flocculant orprecipitant suspended therein into the stilling chamber. Applicants'inlet tube 222 may be seen to have an open removed end 222A, and,adjacent a removed end an angled portion 222B for directing the flow ofliquids into the stilling chamber so as to generate a slow,non-turbulent flow within the chamber. Upstream of the point at whichthe inlet tube enters the main chamber, there may be a degas vent orpipe 224 from which the larger gas bubbles may escape from the liquidbefore it enters the main chamber. Entering the stilling chamber 220through a dissolved air delivery tube 226 is a compressed gas liquidcomposition. The dissolved air delivery tube includes a removed end 226Awhich may include an angled portion 226B in an effort to assist in thecirculation of the fluid in the main chamber to avoid turbulence.Indeed, the function of stilling chamber 24 is to reduce the velocity ofliquid entering the chamber to a point of slow, smooth flow. Stillingchamber 220 also is intended to increase retention time to allow furthercoagulation, flocculation and gas bubble precipitation as well as agrowth of flocculant solid particles. Note that stilling chamber 220 mayinclude a flanged lip 228 adjacent an upper opening thereof and a slopedbottom wall 232, the flanged lip and sloped bottom wall connected byvertical sidewalls 230. The effect of the flanged lip and/or slopedbottom wall is to promote a smooth, slow flow of the liquid and thusprovide increased efficiency. Notice that open bottom 234 of stillingchamber 220 may be located above drain 210 so as to “allow” anyprecipitates descending therefrom to travel toward the drain. Note alsothat the sidewalls of the stilling chamber may include an interiorbaffle 236 projecting into the stilling chamber so as to reduce the flowof liquids therein to, again, promote a smooth non-turbulent slow flowof liquid. Furthermore, the stilling chamber may be supported within themain chamber, above the floor of the main chamber by chamber supportbaffles 238 extending from an inner surface of the vertical sidewalls ofthe main chamber to the sidewalls of the stilling chamber, the supportbaffles having an exaggerated width (vertical dimension) so as to helpminimize currents in the main chamber.

[0068] The main chamber must be provided with a means to remove a liquidtherefrom, the liquid here being removed by outlet channel assembly 240which may consist of a single pipe, having multiple branches 240A, 240Band 240C (see FIGS. 11A and 11B) or a jacket assembly 240D (see FIGS.12A and 12B). By providing for multiple outlets at or near the bottom ofmain chamber 202, Applicants provide for a more efficient removal ofliquid from the gas-assisted flotation apparatus 200, 200A. While threebranches are illustrated in FIG. 11B, any number may be used.

[0069] Applicants may also provide a standing pipe 242 with a catchvessel 244 from which liquid removed from the main chamber throughoutlet channel assembly 240 may be contained, for the control of thelevel of liquid in main chamber 202 and as a source of water for the airdissolving mechanism.

[0070] So long as fluid to be treated is allowed to enter chamber, thefluid will rise to the level of the top of standing pipe 242. This levelmay be adjusted to coincide with the level of the bottom of the sideport214 or to a level just below jets or pressure ports 218D, or to any bothappropriate for the density of the floating phase.

[0071] Thus, Applicants provide a novel gas-assisted flotation processand apparatus that achieves at least the following results: reduction ofturbulence; effective removal of gas/solid material through a removedneck opening; effective maintenance of fluid level adjacent a gas orcompressed air transport tube; an effective drain to removeprecipitates; the angled injection of fluid into a stilling chamber andgas dissolved air from a separate tube into a stilling chamber, thestilling chamber being effectively designed to help reduce turbulence.Dissolved gas is injected through dissolved air delivery to be 226.Water is drawn off the bottom of catch vessel 244. Air pump 244A willinject air into the stream of fluid injected into the stilling chamber.Outlet port 244B will pass water on for further treatment or use.

[0072] Thus, applicants provide a method of transporting a quantity ofwater from a removed location to an electrocoagulation reactor, movingthe water through the electrocoagulation reactor while subjecting thewater to an electric field, then discharging the waste water from theelectrocoagulation reactor through a discharge port. Downstream thedischarge port and inline with discharge piping is a recirculation loopthat includes a pump for recirculating a portion of the water back intothe electrocoagulation reactor by reintroducing the waste water that isalready passed through the reactor at least once upstream of the inletport of the reactor.

I claim:
 1. A method for treating water, the method comprising the stepsof: providing an electrocoagulation reactor having an intake pipe, theintake pipe having a first pump engaged therewith and an intake port anda discharge pipe and a discharge port, the electrocoagulation reactorincluding a recirculation loop with a recirculation pump engagedtherewith; transporting a quantity of water from a distant location tothe intake port of the electrocoagulation reactor via the intake pipeand the first pump; subjecting the water in the reactor to an electricfield; moving the water through the electrocoagulation reactor;discharging the water from the electrocoagulation reactor to thedischarge pipe; and, pumping a portion of the discharged water throughthe recirculation loop and the recirculation pump back into theelectrocoagulation reactor upstream thereof.
 2. The method of claim 1further including the step of: defoaming the water discharged from theelectrocoagulation reactor.
 3. The method of claim 1 further includingthe step of: clarifying the water discharged from the electrocoagulationreactor.
 4. The method of claim 1 further including the step of:providing a settling tank and allowing the water discharged from theelectrocoagulation reactor to reside in the settling tank so that anyparticulate matter may settle out from the water.
 5. The method of claim1 further including the steps of providing a sludge thickener downstreamof the electrocoagulation reactor and residing the water discharged fromthe electrocoagulation reactor in the sludge thickener for thickeningany sludge contained therein.
 6. A device for treating water, the deviceincluding: an electrocoagulation reactor having an intake pipe engagedwith a first pump, an intake port, an outlet pipe and an outlet port;and a recirculation loop having a recirculation pump for taking aportion of the water in the outlet pipe and reintroducing it to theinlet pipe.
 7. The device of claim 6 wherein the recirculation loopincludes a pipe for joining the outlet pipe and for joining the inletpipe downstream of the first pump.
 8. The device of claim 6 wherein thefirst pump is a positive displacement pump.
 9. The device of claim 6wherein the recirculation pump of the recirculation loop is a positivedisplacement pump.
 10. The device of claim 6 wherein theelectrocoagulation reactor has a multiplicity of plates arranged for theseries flow of water there between.
 11. The device of claim 6 whereinthe electrocoagulation reactor has a multiplicity of plates therein forthe parallel flow of water there-between.
 12. The device of claim 6wherein the electrocoagulation reactor includes sealed walls formaintaining positive pressure therein.
 13. A method for treatingwastewater in an electrocoagulation reactor having a first pump upstreamof the electrocoagulation reactor and a recirculation loop including arecirculation pump, the recirculation loop for recirculating wastewaterdischarged from the electrocoagulation reactor back upstream thereof anddownstream of the first pump, the method including the steps of:selecting a net wastewater flow rate; determining an efficientelectrocoagulation reactor flow rate; setting the first pump toestablish the net waste water flow rate there-through; and setting arecirculation pump to establish in the recirculation loop, a flow rateequal to approximately the difference between the electrocoagulationreactor flow rate and the net wastewater flow rate.
 14. A device fortreating water to alter the characteristics thereof, the devicecomprising: a first cell tank; a first multiplicity of paired steelplates, dimensioned for receipt within the first cell tank; means tomount the first multiplicity of steel plates within the first cell tankin parallel, spaced apart arrangement; first inlet means for bringingwater into the first cell tank; and first outlet port for removing waterfrom the first cell tank, wherein means for mounting the firstmultiplicity of paired steel plates, the first inlet means and the firstoutlet port, are adapted to cause each molecule of water entering thecell tank to pass between only a single pair of the first multiplicityof paired steel plates.
 15. The device of claim 14 further comprising: asecond cell tank; a second multiplicity of paired steel platesdimensioned for receipt within the second cell tank; means to mount thesecond multiplicity of paired steel plates into the second cell tank inparallel, spaced apart arrangement; second inlet means for bringingwater into the second cell tank; connecting tube for carrying water fromthe first outlet port to the second inlet means; second outlet port forremoving water from the second cell tank; wherein means for mounting thesecond multiplicity of paired steel plates, the second inlet means andthe second outlet port are adapted to allow each molecule of waterentering the second cell tank to pass between only one pair of thesecond multiplicity of paired steel plates.
 16. The device of claim 14wherein the first cell tank includes a sump and wherein means to mountthe first multiplicity of steel plates includes a cartridge for mountingthe plates thereto, the cartridge having an open bottom and an open top,the mounting means engaging the first cell tank so that the open bottomis above the sump and wherein the first inlet means is located in thesump.
 17. The device of claim 14 wherein the first cell tank includes asump, the sump having tapered walls and having a drain at the bottomthereof, for removal of sediment collected in the sump therefrom. 18.The device of claim 14 wherein means to mount the first multiplicity ofsteel plates includes a cartridge having slotted walls for engaging theplates and walls for resting against an interior of the first cell tankto maintain the position of mounting means within the first cell tank.19. The device of claim 14 wherein means to mount the first multiplicityof steel plates includes a pair of spaced apart, plate engaging sidewalls, one of the pair being lower than the other and spaced apartwithin the first cell tank so as to create a spillover chamber, suchthat water passing between the plates will spill over the lower of theside walls into the spillover chamber of the device and wherein thefirst outlet port is engaged to the walls defining the spilloverchamber.
 20. The device of claim 14 wherein the first cell tank has anopen top and wherein means for mounting includes a cartridge havingslotted walls for engaging the plates and walls for resting against aninterior of the cell tank to maintain the position of the mounting meanswithin the first cell tank, such that it may be lifted out of the opentop of the first cell tank.
 21. The device of claim 14 wherein the meansto mount the first multiplicity of steel plates includes a cartridgehaving slotted walls for engaging the plates and having walls forresting against an interior of the first cell tank to maintain theposition of the mounting means within the cell tank.
 22. The device ofclaim 14 wherein the plates of the first multiplicity of plates have nocutouts.
 23. The device of claim 14 wherein the plates of the firstmultiplicity of plates have cutouts.
 24. The device of claim 14 furthercomprising a dissolved air flotation cell downstream of the first outletport and in fluid communication therewith.
 25. The device of claim 24wherein the dissolved air flotation cell includes a main chamber havingbottom walls and having a tapered upper portion, the upper portionhaving inwardly converging walls culminating at an opening, the mainchamber having an inlet port for receipt of a fluid from the first celltank and an outlet port for removing fluid therefrom.
 26. The device ofclaim 25 wherein the dissolved air flotation cell further includes afluid discharge valve connected to the outlet port for controlling thefluid level in the upper portion of the main chamber.
 27. The device ofclaim 26 wherein the dissolved air floatation cell further includesmeans for injecting a dissolved gas into the fluid residing in the mainchamber.
 28. The device of claim 24 further including a fluid dischargeline connected to the outlet port, wherein said fluid discharge line isin fluid communication with a level control pipe wherein the level offluid will be the same as in the main chamber to control the level offluid in the main chamber.
 29. The device of claim 14 further includinga recirculation pump downstream of the first outlet port for pumping aportion of the water received therefrom to a point upstream of the firstinlet means for recirculation of the flow through the first cell tank.30. The device of claim 15 further including a recirculation pumpdownstream of the second outlet port for pumping a portion of the waterreceived therefrom to a point upstream of the first inlet means forrecirculation through the first cell tank.
 31. The device of claim 15further including a recirculation pump downstream of the second outletport for pumping a portion of the water received therefrom to a pointbetween the two cell tanks for recirculation of some of the fluidthrough the second cell tank.
 32. A dissolved gas flotation device forseparating solids from liquids in a slurry comprising: a main chamberhaving a lower entry channel from which the slurry may enter the mainchamber and having a tapered upper portion terminating in an open apex,the open apex having an upper pipe attached thereto to receiveconsolidated particles which have floated to the top of the liquid orbubbles attached to the solids, the upper pipe having a removed end; afluid discharge pipe; means to control the level of liquid in the mainchamber; and airjets for engagement with the main chamber above thelevel of fluid for driving the solids floated atop the liquid outthrough the removed end of the upper pipe.
 33. The flotation device ofclaim 32 wherein the main chamber includes a tapered lower portion forthe collection of sediment therein, the tapered lower portion includinga drain valve.
 34. The flotation device of claim 32 wherein the levelcontrol means includes a standing pipe in fluid engagement with thefluid discharge pipe.
 35. The floatation device of claim 32 furtherincluding a degas vent upstream of said lower entry channel.
 36. Theflotation device of claim 32 further including a stilling chamberadapted to receive the slurry from the lower entry channel and means tosupport the stilling chamber above the bottom wall of the main chamber.37. The flotation device of claim 36 wherein the lower entry channelincludes an open end terminating in the stilling chamber and angled toinduce a smooth slow flow of slurry in the stilling chamber and furtherincluding means to inject dissolved gas including an airpump connectedto a tube having an open end terminating in the stilling chamber, forintroduction of dissolved gas below the open end of the lower channel.38. The flotation device of claim 36 wherein the stilling chamberincludes baffles.
 39. The flotation device of claim 36 wherein thestilling chamber is open at the bottom.
 40. The flotation device ofclaim 32 wherein the fluid discharge pipe includes a multiplicity ofbranches spaced apart and opening to the main chamber near the bottomthereof.
 41. The flotation device of claim 36 wherein the means tosupport the stilling chamber includes a multiplicity of support vanes.